Mogami Yoshiatsu served as a sengoku daimyō during the early Sengoku period.  He served as the eighth head of the Mogami clan of Dewa Province.

Yoshiatsu was born as the eldest son and designated heir of Mogami Mitsuuji, the seventh head of the Mogami and Commissioner of Dewa.  After the death of Mitsuuji, Yoshiatsu succeeded hm as the eighth head of the clan.  He carried the bloodline of the Dewa-Nakano clan so, at the same time, he also became the head of the Nakano clan, placing Nakano Castle under his direct jurisdiction.  He appointed his second son, Mogami Yoshitatsu, to serve as the head of the Nakano clan based at Nakano Castle.

In 1504, Yoshiatsu died and he was succeeded by his eldest son, Mogami Yoshisada.